Several designs have been proposed to allow for the periodic cleaning of mist eliminator blades (also referred to in the art as plates). One such design, in the U.S. Pat. No. 2,752,005 to Avera for an Eliminator Plate Assembly for Air Washers discloses a clip at one end of each plate, which is hooked over a bar so that the plate hangs from the bar and swings freely so that a plate may be easily spread apart from an adjacent plate. At the other end of the plate a slotted spacer bar holds the other ends of the plates in position, but can be detached for cleaning of the plates.
It has been found in actual use with the exhaust streams of desulfurization units that structures such as that used by Avera U.S. Pat. No. 2,752,005 quickly become clogged, rendering the mist eliminator unit ineffective. In particular, the hooked ends quickly accumulate solids and scale. Therefore, the assembly shown in Avera U.S. Pat. No. 2,752,005 will have an excessive amount of cleaning downtime. Furthermore, due to the nature of the clip and bar combination used to provide a pivot, the invention shown in Avera is difficult to use when inverted, that is, when the pivot end of the plates is located on the bottom side of the plates. In such an orientation the plates are difficult to realign after cleaning so that the spacer bar is fitted onto the free ends of the plates.
U.S. Pat. No. 3,276,193 to Lamb for an Eliminator Plate Assembly for Air Washers discloses an assembly in which the hooked ends of plates are fitted into matching hooks of a core framework.
The Lamp U.S. Pat. No. 3,276,193 invention has also been found to be subject to excessive clogging of the blades in heavy duty applications. The hooked ends of the blades and their mountings quickly accumulate precipitated solids and scale during use, creating the need for frequent cleaning. Furthermore, it has been found that when structures such as that disclosed by Lamb U.S. Pat. No. 3,276,193 are used in a vertical gaseous flow environment such as in a tower, that droplets removed from the gas stream will collect in the hooked ends of the blades, and this collected liquid will be reentrained in the gas stream.
U.S. Pat. No. 3,864,110 to Wyman for a Support Assembly For Eliminator Blades discloses an assembly in which the edges of blades are seated in grooves formed in support bars situated at the top, bottom, and lateral edges of each blade. However, no provision is made in this design for separating individual blades like the pages of a book to clean them.
U.S. Pat. No. 3,870,488 to Arndt for a Liquid Eliminator discloses fitting the hooked ends of a blade into a slotted support bracket. The structure disclosed in Arndt has been found to be extremely prone to clogging and solids accumulation in heavy duty use. The hooked ends of the blades and their supports quickly accumulate both liquids and solids in heavy duty service. These accumulated solids and scale must be manually removed, and this may only be accomplished by a complete disassembly of the mist eliminator. Furthermore, if the invention of Arndt U.S. Pat. No. 3,870,488 is used in a vertical gaseous flow environment such as in a tower, the various trapping vanes and deflectors formed on the blades will fill with trapped droples leading to reentrainment of the droplets, giving a low droplet removal efficiency.
To reduce the problem of clogging by particulates, several inventors have suggested the use of an intermittent or continuous wash water spray on the eliminator blades. For example, in U.S. Pat. No. 4,053,292 to Schneider for a Gas Scrubbing Plant, an intermittent 10 second rinse cycle for each hour of operation is recommended to keep plates clean. U.S. Pat. No. 4,251,242 to Ito for a Mist Eliminator also discloses the use of a wash water spray.
The prior art thus has forcused on various blade holding frameworks which use a pivoting hook and rod combination to allow access to the plates for cleaning. This type of mounting has been found to be subject to rapid clogging and deteriorating efficiency in heavy duty applications, and has also been found to lead to reentrainment of collected liquid when used in a vertical flow tower. The prior art does not provide for a blade module which both obviates solid accumulation and which may be readily cleaned in place either manually or by a method of self-cleaning.